In a statement, E!, which airs Rivers' Fashion Police, and its parent company, NBCUniversal said: "E! and NBCUniversal send our deepest condolences to Melissa, [grandson] Cooper and her entire extended family on this incredibly sad day. For decades, Joan has made people laugh, shattered glass ceilings and revolutionized comedy. She was unapologetic and fiercely dedicated to entertaining all of us and has left an indelible mark on the people that worked with her and on her legions of fans. She’s been a much beloved member of the E! family for over 20 years, and the world is less funny without her in it. Today our hearts are heavy knowing Joan will not be bounding through the doors.”

Comedian David Steinberg added in a separate statement, "She was one of the best comedy guests Johnny [Carson] ever had …”

Barbara Walters said of Rivers: “No one loved life, laughter and a good time more than Joan. We would have dinner and laugh and gossip, and I always left the table smiling. She was a brassy, often outrageous and hilarious performer who made millions laugh. In private, she was the picture of elegance and class. I will miss her."

Israeli prime minister, Benjamin Netanyahu, also remembered Rivers, saying through his media adviser, "Joan Rivers brought laughter to millions around the world and was proud of her Jewish heritage and a vocal supporter of the State of Israel. We will miss her deeply and we send our heartfelt condolences to her family."

Ryan Seacrest said: "Joan was a trailblazer in so many ways, and I greatly admired her talent and humor. She was a colleague and friend, as we worked together on E!, and she was also a treasured guest on my radio show many times. Regardless of the forum, Joan was full of funny, witty surprises and she had so much spirit. She will be greatly missed. My thoughts and prayers go out to Melissa and her family."

Kelly Ripa added in a statement: "Joan Rivers was a pioneer in the entertainment industry. Fearless, tireless and brilliantly funny. I will forever look up to Joan. She was a true friend. My thoughts and prayers are with her family."
---Kelly Ripa

David Letterman, meanwhile, paid tribute to Rivers during Thursday night's Late Show, saying, “Here’s a woman, a real pioneer for other women looking for careers in stand-up comedy. And talk about guts — she would come out here and sit in this chair and say some things that were unbelievable, just where you would have to swallow pretty hard… but it was hilarious… the force of her comedy was overpowering."

Roseanne Barr penned a lengthy tribute to Rivers, who paved the way for her and other female comedians, for The Huffington Post, explaining that she appreciated how Rivers made fun of the societal pressure that made her concerned about her looks, which Barr pointed out “isn't just telling jokes, it's actual layered feminist social critique, of which Joan was a master.”

“She was always surprising us, always defying the status quo, always courageous, loud, opinionated and damning…Joan was constantly praised and then hounded by sexist Hollywood for having an independent point of view and a sense of unmatched female inner power -- no one has ever seen such a fierce woman in any media,” Barr wrote. “She paid the cost to be the boss. Most comics couldn't hold up mentally to the kind of humiliation that Hollywood put Joan Rivers through. She turned it all back on their sexism though, like St. Joan the Conquerer. She kept getting braver and braver.”

Barr added that she was hoping Rivers would recover from her hospital scare but her death was one final surprise.

“I wanted her to beat death's ass down, too, and prayed for that to happen, but she took her last curtain call instead, surprising me one last time,” she wrote. “You controlled the room always, in the most professional way, too. You leveled the playing ground for all comedians. You'll be missed, but not forgotten. Copied but never matched. Never bested.”

Here's more of what Hollywood said about Rivers on social media:

Recalling when she burst onto the Tonight Show scene when I was a kid - #RIP Joan Rivers